Analysis of stable components for extended-range (10-30 days) weather forecast:A case study of continuous overcast-rainy process in early 2009 over the mid-lower reaches of the Yangtze River  

作　　者：FENG GuoLin SUN ShuPeng ZHAO JunHu ZHENG ZhiHai 

机构地区：[1]Laboratory for Climate Studies,National Climate Center,China Meteorological Administration [2]College of Atmospheric Sciences,Lanzhou University

出　　处：《Science China Earth Sciences》2013年第9期1576-1587,共12页中国科学（地球科学英文版）

基　　金：supported by National Natural Science Foundation of China (Grant No.40930952);Science and Technology Supporting Project (Grant No.2009BAC51B04)

摘　　要：A continuous overcast-rainy weather(CORW) process occurred over the mid-lower reaches of the Yangtze River(MLRYR) in China from February 14 to March 9 in 2009,with a large stretch and long duration that was rarely seen in historical records.Using the empirical orthogonal function(EOF),we analyzed the geopotential height anomaly field of the NCEP-DOE Reanalysis II in the same period,and defined the stable components of extended-range(10-30 days) weather forecast(ERWF).Furthermore,we defined anomalous and climatic stable components based on the variation characteristics of the variance contribution ratio of EOF components.The climatic stable components were able to explain the impact of climatically averaged information on the ERWF,and the anomalous stable components revealed the abnormal characteristics of the continuous overcast-rainy days.Our results show that the stable components,especially the anomalous stable components,can maintain the stability for a longer time(more than 10 days) and manifest as monthly scale low-frequency variation and ultra-long-wave activities.They also behave as ultra-long waves of planetary scale with a stable and vertically coherent structure,reflect the variation of general circulation in mid-high latitudes,display the cycle of the zonal circulation and the movement and adjustment of the ultra-long waves,and are closely linked to the surface CORW process.A continuous overcast-rainy weather（CORW） process occurred over the mid-lower reaches of the Yangtze River（MLRYR） in China from February 14 to March 9 in 2009,with a large stretch and long duration that was rarely seen in historical records.Using the empirical orthogonal function（EOF）,we analyzed the geopotential height anomaly field of the NCEP-DOE Reanalysis II in the same period,and defined the stable components of extended-range（10-30 days） weather forecast（ERWF）.Furthermore,we defined anomalous and climatic stable components based on the variation characteristics of the variance contribution ratio of EOF components.The climatic stable components were able to explain the impact of climatically averaged information on the ERWF,and the anomalous stable components revealed the abnormal characteristics of the continuous overcast-rainy days.Our results show that the stable components,especially the anomalous stable components,can maintain the stability for a longer time（more than 10 days） and manifest as monthly scale low-frequency variation and ultra-long-wave activities.They also behave as ultra-long waves of planetary scale with a stable and vertically coherent structure,reflect the variation of general circulation in mid-high latitudes,display the cycle of the zonal circulation and the movement and adjustment of the ultra-long waves,and are closely linked to the surface CORW process.

关 键 词：Analysis of stable components for extended-range （10-30 days） weather forecast：A case study of continuous overcast-rainy process in early 2009 over the mid-lower reaches of the Yangtze River 

分 类 号：P457.6[天文地球—大气科学及气象学]